Figure 3
From: Ardissonea crystallina has a type of sexual reproduction that is unusual for centric diatoms
Male gametogenesis in Ardissonea crystallina (C. Agardh) Grunow. (a–d) The contents of the male gametangium shrink from both ends of the cell to form an ellipsoidal gamete positioned in the centre of the gametangial frustule. The gamete transapical dimension increases and as a result the gametangial thecae becoming slightly opened (arrow). (e) Chloroplasts are densely aggregated in the remaining cytoplasm. (f) Finally, the male gamete becomes spherical, in contrast to (g) the female gamete which does not escape from the gametangium frustule and fills it (arrow: male gamete, double arrow: female gamete). Scale bars (a–g) = 20 µm.
